I did that once, and it worked like a dream, but I hated the looks of phpmyadmin (maybe the oldest layout ever) and decided to delete it, and didn't know that deleting is done with apt-get remove phpmyadmin and did in phpmyadmin directory rm * and thought that it's done. However, as I can't find the debian build of phpmyadmin anywhere, I want to install it again, but when I add Include /etc/phpmyadmin/apache.conf to /etc/apache2/apache2.conf, and restart apache, it give's me this error:

apache2: Syntax error on line 73 of /etc/apache2/apache2.conf: Could not open configuration file /etc/phpmyadmin/apache.conf: No such file or directory
Action 'configtest' failed.
The Apache error log may have more information.
failed!

No matter how I try, I always get this error, and phpmyadmin isn't there.

Removing configuration files is considered to be a configuration change, and Debian packages are required to preserve configuration changes. So reinstalling a removed package will not cause removed configuration files to be restored. You need to purge the package rather than just remove. This will tell the packaging system that you no longer want even the configuration files for the package. Once that is done you can install the package again and the configuration files will be reinstalled as well.